wrapped command to avoid errors for uninstalled objects

islandora.drush.inc

@@ -177,10 +177,11 @@ function drush_islandora_solution_pack_install_content_models() {
     $objects_to_add = array();
     foreach ($info['objects'] as $key => $candidate) {
       $object = islandora_object_load($candidate);
-      if (in_array('fedora-system:ContentModel-3.0', $object->models)) {
+      if ($object && in_array('fedora-system:ContentModel-3.0', $object->models)) {
         $objects_to_add[] = $candidate;
       }
     }
+    if (count($objects_to_add) > 0) {
       foreach ($objects_to_add as $object_to_add) {
         $old_object = islandora_object_load($object_to_add->id);
         if ($old_object) {
@@ -197,4 +198,5 @@ function drush_islandora_solution_pack_install_content_models() {
         }
       }
     }
+  }
 }